Literature Review of Radiographic Measurements of Internal Organs in Psittaciformes

REVIEW LITERATURE REVIEW OF RADIOGRAPHIC MEASUREMENTS OF INTERNAL ORGANS IN PSITTACIFORMES

Lise Geerinckx, DVM, Elke Van der Vekens, DVM, Dip. ECVDI, Jimmy H. Saunders, DVM, PhD, Dip. ECVDI, Ines Lautenschlager,€ DVM, and Annemie I.L. Van Caelenberg, DVM, PhD

Abstract This review article contains the published measurements and ratios of the different coelomic organs in birds including the heart, proventriculus, and liver. Radiographic examination of birds is becoming very important in the daily diagnostic assessment of patients presented to veterinary hospitals. When a veterinarian is treating birds, it is crucial to have a broad theoretical knowledge of the subject as well as sufﬁcient practical experience. However, there may be some help for the less experienced veterinarian as they assess their avian patients with primary diagnostic options. The measurement techniques and the interpretation of avian radiographic examinations are described in this article, so that veterinarians can easily use this information as a guide in practice. The heart and liver size are evaluated on ventrodorsal radiographs. For heart width, a ratio with the cranial coelom and/or coracoid has been determined while the liver dimensions can be interpreted by comparing it to the size of the caudal coelom. The other internal organs are interpreted on lateral radiographic images. The best way to evaluate the diameter of the proventriculus is through comparison of the organ to the height of the keel of the sternum. For kidneys, spleen, and gonads, no exact formulas have been published at this time. However, kidney size can be evaluated by a line that is drawn parallel to the spine that extends through the ventral border of the acetabulum. Healthy kidneys should not extend ventrally to this line. By combining all of the radiologic measurements described in this article with anamnesis and clinical examination, the information may assist the veterinarian in obtaining a correct diagnosis which would result in the optimal treatment for disease condition affecting the avian patient. Copyright 2018 Elsevier Inc. All rights reserved. Key words: bird; coelomic cavity; internal organs; psittaciformes; radiography

xotic animals, including parrots, have become popular pets, which has resulted in more avian visits to veterinary hospitals. Since all veterinarians are not familiar with avian medicine, the health of the birds might be at risk because treatment of avians often requires very speciﬁc care. Before one initiates their avian medicine practice, it is important to have a broad-based theoretical knowledge of the subject as well as sufﬁcient practical experience. However, there Emay be some options to assist the less experienced veterinarian with primary diagnostic test interpretation which includes radiographic imaging.

From the Dierenartsencentrum Trigenio, Nijlen, Belgium; and the Department of Veterinary medical imaging and small animal, Faculty of Veterinary Medicine, University of Ghent, Merelbeke, Belgium Address correspondence to: Lise Geerinckx, Dierenartsencentrum Trigenio, Dorsel 38, B-2560 Nijlen, Belgium. E-mail: [email protected] Ó 2018 Elsevier Inc. All rights reserved. 1557-5063/14/2101-$30.00 https://doi.org/10.1053/j.jepm.2018.08.001

60 Journal of Exotic Pet Medicine 28 (2019), pp 60À68 Parrots, the order of Psittaciformes, are a group of The objective of this project was to gather all exotic birds, of which there are 3 families with very information from radiographic studies reported diverse characteristics. Psittacidae or “true” parrots in Psittaciformes and other avian species. consist of a large group of different species.1 Radiographic measurements can be a rather Psittacidae contains all macaws (Ara) and amazon simplified means to help an unexperienced avian species (Amazona). The extremely popular grey veterinarian a rapid assessment regarding certain parrot (Psittacus erithacus) and the Senegal parrot aspects of a bird’s health. However, one must (Poicephalus senegalus) also belong to this family. remember to always link the radiographic Some other well-known examples of Psittacidae are interpretations to the clinical examination of the lovebirds (Agapornis), budgerigars (Melopsittacus patient. Clinical evaluation of the bird always undulatus), ringnecks (Psittacula krameri) and remains the most important step in the eclectus parrots (Eclectus roratus). The family examination of the patient. Psittacidae also contains the large group of lorikeets and lories, with the well-known Rainbow lorikeet DISCUSSION (Trichoglossus haematodus). Well-known pet birds in the Cacatuidae or Heart cockatoos family are the Galah or Rose-breasted Cockatoo (Eolophus roseicapilla) and the Umbrella The heart has been well studied in birds with many Cockatoo (Cacatua alba). The very popular reference measurements of this vital organ already cockatiel (Nymphicus hollandicus) also belongs to available. Antemortem diagnosis of heart disease in parrots is very important because older birds are this family. 3 Strigopidae are rather rare birds, for example, the known to develop heart pathology. A recent Kea (Nestor notabilis) and the Kakapo (Strigops retrospective study reported that necropsy habroptila), that are not kept as pets and thus are examinations diagnosed (undiagnosed) congestive heart failure in 9.7% of a total of 269 out of the scope of this article. 4 Radiography is a valuable tool when diagnosing Psittaciformes. Consequently, developing reliable pathology in birds. However, it is extremely antemortem methods to diagnose heart disease is important that a full clinical examination of the important with radiographic imaging being one. patient is first performed prior to obtaining Except for cockatoos, a parrot’s cardiac silhouette radiographic images. The preliminary physical should always be evaluated on a ventrodorsal examination will direct the veterinarian in a more radiograph because the alignment in the lateral projection is often not identified due to extensive diagnostic approach and is necessary to 5,6 appropriately interpret the radiographic images of summation with the liver. Cockatoos have the patient. Similar to dogs and cats, the size of cranial coelomic air sacs delineating their cardiac certain organs in birds can be an indicator of silhouette, which makes it possible in these species to use lateral projections to analyze their cardiac specific diseases. Therefore, measurements and 5 evaluation of coelomic organs (e.g., heart, silhouette. proventriculus, liver, and kidneys) can help one The relevance of 6 measurements has been diagnose a disease condition in a sick bird. studied on a ventrodorsal radiograph (Fig. 3): When analyzing the radiographic images of a parrot, it is important to know the exact species, 1 The width of the heart (A-B); due to inter-species differences. Therefore, the 2 The width of the cranial coelom (C-D); species will be mentioned with each radiographic 3 The width of the coracoid (E-F); image in this article. Preferably 2 orthogonal 4 The distance between the third and fourth rib radiographic images are made: a ventrodorsal and (G-H); lateral projection. These images must be as 5 The width of the synsacrum (I-J); symmetrical as possible, thus avoiding rotation 6 The distance between the clavicles (K-L). that would give an incorrect measurement of the organ size. In Figures 1 and 2, the important organs Instructions on how to perform these evaluated in this article are presented. measurements correctly are provided below: Radiographic measurements of organs depend on several factors including size of the bird and the The width of the cardiac silhouette is measured distance between the bird and the radiography at its widest point and the width of the cranial cassette. Therefore, ratios are mandatory to coelom is measured at the exact same level. compare the size of the organs among different The width of the coracoid is measured immedi- patients.2 ately caudal to the shoulder joint.

Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68 61 FIGURE 3. Ventrodorsal radiograph of a rainbow lorikeet (Trichoglossus haematodus) indicating the FIGURE 1. Ventrodorsal radiograph of a blue-and-yellow different measurements relevant for assessing the heart: macaw (Ara ararauna), showing the different organs the width of the heart (A-B), the width of the cranial described in this article. The heart is shown in red (1) and coelom (C-D), the width of the coracoid (E-F), the the liver is shown in blue (2). distance between the third and fourth ribs (G-H), the Picture is property of the Faculty of Veterinary width of the synsacrum (I-J), and the distance between Medicine UGent, Department of Medical Imaging of the clavicles (K-L). Animals and Orthopedics of Small Animals, 2015. Picture is property of Dierenartsencentrum Trigenio, 2013.

The distance between the third and fourth rib is measured next to and parallel to the spine. The width of the synsacrum is measured at its widest point. The distance between the most cranial points of the clavicles is measured cranial of the shoulder joint.

Multiple studies have been performed in which the relation of the abovementioned measurements and the cardiac health have been examined.

The width of the heart is unrelated to weight FIGURE 2. Lateral radiograph of an African grey parrot and sex of the bird.7 (Psittacus erithacus) that shows the different organs The width of the heart is related to the width of described in this article. Proventriculus is shown in green the cranial coelom, the width of the coracoid (1), spleen is shown in bordeaux (2), gonads are shown 6-8 in purple (3), and kidneys are shown in blue (4). and the length of the sternum. Picture is property of the Faculty of Veterinary No other attempt to determine meaningful Medicine UGent, Department of Medical Imaging of ratios relevant to the health of the heart gave Animals and Orthopedics of Small Animals, 2015. conclusive results.7 The distance between the

62 Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68 third and fourth rib, the width of the synsacrum coelom is width of the heart (mm) = 6.014 + width or the distance between the clavicles did not of the cranial coelom (mm) £ 0.273.7 In a give conclusive results relevant to the health of published study, it was determined that the the heart, therefore, cannot be used as relevant absolute width of the heart in budgerigars measurements. (Melopsittacus undulatus) is 9.5 to 12.0 mm, with a Enlargement of the cardiac silhouette is not nec- mean value of 10.8 mm. Since absolute values were essarily the result of dilatation of the heart itself used in this study instead of ratios, standardization because pericardial fat or distention of the gas- of the radiographs was extremely important. A tro-intestinal system can give the exact same commercial X-ray unit with a mammographic radiographic image.8 Therefore, every radio- cassette and film and a focus film distance of graphic finding needs to be confirmed by a clini- 100 mm was used for the budgerigar radiographic cal diagnosis.7 images. A formula applied for other bird species, All existing measurements related to the cardiac including eastern screech owls (Megascops asio), silhouette were obtained for a specific study and a red-tailed hawks (Buteo jamaicensis), and Canada specific species. Some of these studies were geese (Branta canadensis), was based on the specifically performed on Psittaciformes, but other maximum width of the heart and the width of the studies mentioned in the text below were executed sternum and the cranial coelom.9 All 3 on other avian species. It is possible to extrapolate measurements were made at the level of the the measurement principles to different bird maximum width of the heart, as observed on a species, but the results should be confined to 1 ventrodorsal projection. Depending on the avian species.9 species being radiographed, other values must be Studies on multiple parrot species show similar filled in. The formula determined for Canada geese correlations between measurements.8 Moreover, in the published study was as follows: width of the no significant differences were observed between heart (mm) = 15.15 + 0.27 £ (width of the sternum studies on grey parrots (Psittacus erithacus), Senegal [mm]) + 0.21 £ (width of the cranial coelom parrots (Poicephalus senegalus) or orange-winged [mm]).9 amazon parrots (Amazona amazonica). In all 3 This formula is useful but extremely difficult to parrot species mentioned above, the width of the apply, especially in practice. cardiac silhouette was determined to be 51% to 61% of the width of the cranial coelom, 545% to 672% of the width of the coracoid, and 35% to Proventriculus 41% of the length of the sternum. Since the proventriculus is often diseased, it is an The same measurements reveal a similar essential organ to assess through radiographic correlation in a Falconiformes study performed on examination. One of the most common Harris’ hawks (Parabuteo unicinctus), peregrine proventricular disease conditions diagnosed in falcons (Falco peregrinus), saker falcons (Falco parrots (Psittaciformes) is the “Proventricular cherrug) and lanner falcons (Falco biarmicus).6 Dilatation Syndrome,” which results in an enlarged Depending on the specific species, the width of the proventriculus.10 However, one must understand cardiac silhouette was assessed as 54% to 74% of that not every enlarged proventriculus is the width of cranial coelom and 525% to 1000% of pathologic. There are many cases where the width of the coracoid. physiological differences in the size of the A study on healthy peregrine falcons (Falco proventriculus have been reported (e.g., nestlings peregrinus) reported that using the width of the have a relatively large proventriculus, hand rearing cranial coelom to interpret the width of the cardiac results in a larger proventriculus, eclectus parrots silhouette is dependent on the respiratory cycle of (Eclectus roratus) have a relatively large the bird.10 On a lateral radiograph, the length of proventriculus, compared with other parrots).11-13 the cardiac shadow of the peregrine falcon was It is important to consider these physiologic measured as 52% to 64% of the length of the differences when interpreting measurements of the sternum. These measurements have not been proventriculus. accomplished on a parrot species, especially The proventriculus is best viewed on a symmetric because of the difficulty distinguishing the cardiac lateral image. However, slightly rotated apex from the liver on lateral projections. radiographs are acceptable since the proventriculus Another formula that could specifically be used is a symmetrical fusiform organ. to determine the width of the cardiac silhouette in Occasionally, the proventriculus cannot be parrots, again based on the width of the cranial clearly delineated.14 Those images should not be

Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68 63 used for organ assessment since there is a greater The distance between the dorsal border of the chance of providing an incorrect interpretation. proventriculus and the dorsal edge of the ster- When a patient has hepatomegaly, the num is measured at the same location as the proventriculus will be dorsally elevated. lf the maximum coelomic height. proventriculus is filled with gas, its borders will be easier to distinguish. Furthermore, both hepatomegaly and a gas-filled proventriculus will make it easier to measure the proventricular The study by Dennison et al. used multiple ratios diameter. Four measurements have been analyzed to analyze the condition of the proventriculus in 11 for the proventriculus in birds (Fig. 4), the height birds. More specifically, the Dennison study of the proventriculus (A-B), the height of the compared birds with and without gastro-intestinal sternum (C-D), the coelomic height (E-F), and the clinical signs with multiple species of Psittaciformes distance between the dorsal edge of the being evaluated including macaws (Ara spp.), proventriculus and the dorsal edge of the sternum Amazon parrots (Amazona spp.), African grey (E-G). parrots (Psittacus erithacus erithacus), cockatoos The authors have provided some instructions on (Cacatua spp.), and cockatiels (Nymphicus 11 how to execute these radiographic proventricular hollandicus). Significant differences in all ratios measurements correctly: analyzed were identified. The proventricular height—sternal height ratio led to the most correct interpretation, 20% to 47.6% in birds without The height of the proventriculus is measured at abnormal gastro-intestinal clinical signs and 52.2% the point where the thoracic vertebrae develop to 163.2% in birds with clinical disease signs.11 A into the synsacrum. value of 52% and more will therefore be an The height of the sternum is measured at its indication of gastro-intestinal problems. It is highest point, i.e., immediately caudal to the important to realize that, although this ratio can be junction with the coracoid bones and perpen- used as a diagnostic factor, it should not be used as dicular to the dorsal border of the sternum.14 a prognostic factor. There is absolutely no The maximum coelomic height is measured at association between the size of this ratio and the the proximal proventriculus, perpendicular to survival chances of the bird after 1 month.14 the spine. The measurement extends to the ventral aspect of the thoracic vertebrae up to the Liver dorsal border of the sternum. There is not much information currently available regarding the radiographic measurements of the avian liver although it would be interesting because liver disorders in birds are not easy to diagnose. The problematic diagnosis is explained by the vague clinical disease signs associated with liver pathology and the fact that liver enzymes are not often increased in chronic liver disease. Therefore, imaging techniques (e.g., radiography, ultrasonography) can be useful tools in the diagnosis of liver pathology. The size of the liver depends on the species and the body condition of the bird being examined, although this is more significant in pigeons (Columbiformes) than in parrots (Psittaciformes).15 Two orthogonal radiographs are necessary for a FIGURE 4. Right lateral radiographic image of a blue- fronted Amazon (Amazona aestiva) indicating the thorough assessment of the liver. Differentiating different measurements potentially relevant for the the liver from the surrounding organs on lateral normal anatomy of the proventriculus: height of the radiographic images is difficult. Therefore, the proventriculus (A-B), height of the sternum (C-D), ventrodorsal projection will be the most beneficial coelomic height (E-F), and distance between the dorsal to measure the liver. When viewing ventrodorsal edge of the proventriculus, and the dorsal edge of the sternum (E-G). radiographs, the liver in combination with the Picture is property of the Faculty of Veterinary cardiac silhouette should look like an hourglass. A Medicine UGent, Department of Medical Imaging of waist line should be visible between the heart Animals and Orthopedics of Small Animals, 2008. cranially and the liver caudally.2

64 Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68 obtained this measurement is then compared with the maximal width of the cardiac silhouette.16 A ratio is formed between the total width of the heart is measured at its maximal width and the total width of the liver is measured at its maximal width. In male Gyr falcons (Falco rusticolus), the ratio was 1, while in female Gyr falcons it was 1.5. In male Gyr hybrid falcons (Falco rusticolus £ Falco peregrinus), the ratio was 1.4, in female Gyr hybrid falcons it was 1. There are some important considerations for veterinarians to observe when evaluating the hepatic silhouette on radiographic images of avian patients. The right half liver/half caudal coelom ratio is higher than 50% in cases where the liver was diagnosed as enlarged. Other radiographic ﬁndings associated with an enlarged liver in birds include loss of the hourglass shape, rounded edges of the organ, compression of the airsacs, cranial displacement of the heart, and caudodorsal displacement of the proventriculus. Caliendo et al. found that the ratios between heart and liver width were very consistent between birds of the same species; however, differences were observed between sexes.16 This speciﬁc ratio was not yet examined in Psittaciformes. However, it is important to rule out cardiac pathology in cases of suspected hepatomegaly since liver problems can be FIGURE 5. Ventrodorsal radiograph of a blue-and- yellow macaw (Ara ararauna). The measurements shown associated with heart disease. are the width of the right half of the liver (B-C), width of Microhepatica is uncommon but is also known the right half of the caudal coelom (A-C), and maximum to occur in birds, especially macaws (Ara) and width of the liver (D-E). cockatoos (Cacatua) that are fed a seed only Picture is property of Dierenartsencentrum Trigenio, diet.2,15 2014.

Two different ratios concerning measurements of Kidneys the hepatic width were examined from previously A lateral radiographic view is used to analyze the published articles (Fig. 5). The ﬁrst report measures kidneys of a bird since it is nearly impossible to the size of the right half of the liver by evaluating visualize the organs on a ventrodorsal projection the size of the right half of the liver in relation to due to the synsacrum and intestinal summation. In the width of half of the caudal coelom.2 Therefore, most cases, the kidney closest to the cassette is the two measurements required for the better evaluated on the lateral radiographic image. radiographic assessment of right liver size are the Therefore, when there is a high suspicion of renal width of the right half of the liver and the width of pathology, it is best to take 2 (left to right and right the right half of the caudal coelom. to left) lateral images.17 The measurements described above are achieved The cranial pole of the kidney is often the only as follows: the right half of the caudal coelom is visible part of the organ on lateral images because measured at the apex of the cardiac silhouette by the middle and caudal poles are superimposed on connecting the middle of the sternum with the the synsacrum.17-19 Fortunately, for the lateral aspect of the ribs; the right half of the liver is veterinarian, when an avian patient has renal measured at the same level by connecting the pathology, it is frequently the cranial pole of the middle of the sternum with the lateral aspect of the kidney that will enlarge. The height of the cranial liver. pole is therefore likely to be a better measurement The second technique to evaluate the liver is by for renomegaly than the total length of the kidney. measuring the total width of the hepatic silhouette. To interpret the size of the kidneys, a line is Once the total width of the hepatic silhouette is drawn, that runs parallel to the spine and extends

Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68 65 FIGURE 7. Left lateral radiographic image of an African FIGURE 6. Left lateral radiographic image of a macaw grey parrot (Psittacus erithacus). Two orthogonal (Ara). The kidneys should not extend ventrally to a line measurements are obtained to determine the diameter of parallel to the spine through the ventral border of the the spleen (A-B and C-D). acetabulum (A-B). Picture is property of the Faculty of Veterinary Picture is property of the Faculty of Veterinary Medicine UGent, Department of Medical Imaging of Medicine UGent, Department of Medical Imaging of Animals and Orthopedics of Small Animals, 2015. Animals and Orthopedics of Small Animals, 2008.

through the ventral border of the acetabulum (Fig. 6; A-B). Healthy kidneys should not extend ventrally to this line, otherwise renomegaly is present.19 Assessment of renal measurement was speciﬁcally examined in budgerigars (Melopsittacus undulatus).19 Other radiographic signs that suggest renomegaly are a ventral displacement of the proventriculus, ventriculus, and intestinal tract.

Spleen and gonads There are no known radiographic reference FIGURE 8. Left lateral radiographic image of a Cuban measurement values for these 2 organs. Diseases of amazon parrot (Amazona leukocephala). Two orthogonal measurements were obtained to determine the diameter the spleen are less common and therefore of the gonads (A-B and C-D). radiographic measurements are less valuable. Picture is property of the Faculty of Veterinary However, it may be useful to have at least an idea Medicine UGent, Department of Medical Imaging of of the normal size of the avian spleen. Pathology of Animals and Orthopedics of Small Animals, 2012. the ovary is more common in birds, especially in Anseriformes, Galliformes, Strigiformes, Cuculiformes, and Psittaciformes.20 Psittacine birds diagnosed most often with ovarian disease are budgerigars observed as rounded structures. The spleen is (Melopsittacus undulatus) and cockatiels (Nymphicus located directly caudal to the transition of the hollandicus).20 The most common type of ovarian proventriculus to ventriculus. The gonads are neoplasia diagnosed in birds is adenocarcinoma.20 visible cranioventrally to the cranial pole of the Spleen and gonads are not always visible on kidneys. It is important to differentiate the gonads radiographic images of the coelom. Gonads will be from renomegaly. The measurements that are visible when the bird is sexually active at the time recommended for both the spleen and gonads are the radiograph is obtained. When gonadal disease from 2 orthogonal directions (height and length; is present, the organs will also be clearly visible. If Figs. 7 and 8). Often the spleen as well as the gonad the spleen and/or gonads are present, they are both is a rounded structure in Psittacine species,

TABLE 1. Overview of which radiographic image should be used for measurements of which organ Heart Proventriculus Liver Kidneys Gonads Spleen Lateral image Cockatoos X X X X Ventrodorsal image X X

66 Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68 50% (borderline to 52.2%) < through the ventral border of the acetabulum X No ratio or reference values published yet

FIGURE 9. Schematic drawing of a ventrodorsal

Xradiograph Should not extend ventrally of to a line parallel to a the spine parrot. Measurements of heart and liver are shown: maximal width of the heart (A-B) and the width of the cranial coelom at that location (C-D), width of the right part of the liver (E-F) and width of the caudal coelom at that location (G-F), maximal width of the liver (H-I) and width of the coracoid (J-K).

therefore, 1 measurement will sufﬁce to interpret the diameter of the organ.

Heart Proventriculus Liver Kidneys Gonads Spleen Formula Normal Value CONCLUSION Table 1 summarizes which radiographic images are best used to measure the speciﬁc coelomic organ listed. It is important to realize that for a full radiographic examination 2 projections are mandatory. Table 2 provides an overview of which measurements have been useful to analyze the coelomic organs discussed in this article. All measurements used for the ratios are summarized in schematic drawings shown in Figures 9 and 10. The best method to assess the size of the avian heart was determined to be the ratio of the a line parallel to the spinethe and ventral through edge of the acetabulum cardiac silhouette to the width of the cranial coelom, to the width of the coracoid and/or to the TABLE 2. Overview of the radiographic measurements and ratios published in literature 89 Width of the liver10 Height of the Position cranial of pole the of kidneys the in kidney relation to X X No ratio or reference values found yet 1/8 Not yet published 11 Diameter12 of the gonads Diameter of the spleen X No ratio or reference values published yet 12 Width of the heart3 Width of the thorax4 Width of the coracoid5 Height of the proventriculus Height of the sternum X X X X X X 1/2 1/3 4/5 51% to 545% 61% to 672% 20% to 47.6% 67 Width of the right half of Width the of liver the right half of the abdomenlength of X the X sternum. The ﬁrst 2 measurements 6/7

Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68 67 4. Oglesbee BL, Oglesbee MJ: Results of postmortem examination of psittacine birds with cardiac diseases: 26 cases (1991-1995). J Am Vet Med Assoc 212:1737–1742, 1998 5. Pees M, Krautwald-Junghanns M-E: Cardiovascular physi- ology and diseases of pet birds. Vet Clin North Am Exot Anim Pract 12:81–97, 2009 6. Barbon AR, Smith S, Forbes N: Radiographic evaluation of cardiac size in four Falconiform species. J Avian Med Surg 24:222–226, 2010 7. Velayati M, Mirshahi A, Razmyar J, et al: Radiographic reference limits for cardiac width of budgerigars (Melopsittacus undulatus). J Zoo Wildl Med 46:34–38, 2015 8. Straub J, Pees M, Krautwald-Junghanns M-E: Measurement of the cardiac silhouette in psittacines. J Am Vet Med Assoc 221:76–79, 2002 FIGURE 10. Schematic drawing of a lateral radiograph 9. Hanley CS, Murray HG, Torrey S, et al: Establishing cardiac of a parrot. Measurements are shown: height of the measurement standards in three avian species. J Avian Med sternum (A-B), height of the proventriculus (C-D), Surg 11:15–19, 1997 diameter of the spleen (E-F), diameter of gonad (G-H), 10. Lumeij JT, Shaik MAS, Ali M: Radiographic reference limits and height of the cranial pole of the kidney (I-J). for cardiac width in peregrine falcons (Falco peregrinus). J Am Vet Med Assoc 238:1459–1463, 2011 11. Dennison SE, Paul-Murphy JR, Adams WM: Radiographic are the most commonly used in veterinary practice determination of proventricular diameter in psittacine and are the most correct. The proventricular size is birds. J Am Vet Med Assoc 232:709–714, 2008 best measured by using the ratio between the 12. Flammer K, Clubb SL: Neonatology, in Ritchie BW, height of the proventriculus and the height of the Harrison GJ, Harrison LR (eds): Avian Medicine: Principles sternum. and Application, Del Ray Beach, FL, HBD International p. 817, 1999 To diagnose hepatomegaly, 2 different ratios are 13. Gancz AY, Clubb S, Shivaprasad HL: Advanced diagnostic possible. The ﬁrst is to measure between the right approaches and current management of proventricular half of the liver and the right half of the caudal dilatation disease. Vet Clin North Am Exot Anim Pract coelom. The second is calculating the maximum 13:471–494, 2010 width of the liver and the maximum width of the 14. Dennison SE, Adams WM, Johnson PJ, et al: Prognostic accuracy of the proventriculus: keel ratio for short-term heart. survival in psittacines with proventricular disease. Vet No reference values have been reported to Radiol Ultrasound 50:483–486, 2009 properly measure the cranial pole of the kidneys, 15. Krautwald-Junghanns M-E, Zebisch K, Enders F, et al: Diag- spleen, and gonads of avian species. However, nosis of liver disease in birds by radiography and ultraso- since these values could be useful for a veterinary nography: under special consideration of ultrasound- guided liver biopsies. Semin Avian Exot Pet Med clinician treating birds, after more research, they 10:153–161, 2011 are added in the table. The size of the kidneys can 16. Caliendo V, Middelton R, Raghav R: Radiographic mea- also be evaluated using the parallel line through surement of internal organs in Gyrfalcons (Falco rusticolus) the ventral border of the acetabulum. and Gyr peregrine hybrids (Falco rusticolus x Falcoperegri- nus). J Exot Pet Med 25:13–17, 2016 17. Pollock C: Diagnosis and treatment of avian renal disease. REFERENCES Vet Clin North Am Exot Anim Pract 9:107–128, 2006 18. McMillan MC: Imaging of avian urogenital disorders. Pro- 1. Handbook of the Birds of the World: Alive version. Barce- ceedings of the Annual Conference of Association of Avian lona, Spain, Lynx Edicions Veterinarians, Houston, Texas 2:74-82, 1988 2. McMillan MC: Imaging techniques, in Ritchie BW, 19. Simova-Curd S, Nitzl D, Mayer J, et al: Clinical approach to Harrison GJ, Harrison LR (eds): Avian Medicine: Principles renal neoplasia in budgerigars (Melopsittacus undulatus). J and Application, Lake Worth, Florida, Wingers Publishing. Small Anim Pract 47:504–511, 2006 p. 254, 1994 20. Lightfoot TL, Garner MM: Overview of tumors, in Harrison GJ, Lightfoot TL (eds): Clinical Avian Medicine 3. Krautwald-Junghanns M-E, Braun S, Pees M, et al: Research of the anatomy and pathology of the psittacine heart. J (Vol II), West Palm Beach, Florida, Spix Publications, pp Avian Med Surg 18:2–11, 2004 562–569, 2006

68 Geerinckx et al./Journal of Exotic Pet Medicine 28 (2019), pp 60À68